It's all about boundaries. You need to think about what your boundaries are and how you will enforce them. She sounds like she wants to cake eat, ie have her nice domesticated H and enjoying family life while her other life is being a GGW. If it was me I would start living life as if you were on your own. If you are S then be S, no family dinners. This might be brash, but you might even consider charging her rent to board her horse.
H(37) W(35) D8, D5, S3 T20, M13 BD 8/31/18 EA Discovered 9/13/18 Mediation 10/3/18 W files for D 10/12/18 W moves out 11/10/18 EA confirmed 12/25/18 D Final 1/10/19